1. Field of the Invention
The present invention relates to a display apparatus which displays an image using a liquid crystal panel. Particularly, the present invention relates to a display apparatus which has a holding structure of a sheet capable of preventing an occurrence of problems such as luminance unevenness, or a decrease in luminance due to wrinkles, deflection, damage, or the like of an optical sheet used in the display apparatus, while thinning the display apparatus.
2. Description of Related Art
A display apparatus using a liquid crystal panel is provided with an optical sheet for diffusing or collecting light emitted from a light source. The optical sheet is provided between the liquid crystal panel and the light source.
The optical sheet includes one or a plurality of optical films. The optical sheet is mainly thermally expanded due to heat from the light source. Thereby, the optical sheet is held with a margin given by as much as the expansion, in such a way that only a part thereof is hooked to a positioning member. For example, the optical sheet is a rectangular shape, and is provided with a plurality of holes in an edge part on one long side thereof. The optical sheet is hooked to the positioning member by penetrating the positioning pins provided on the positioning member into the plurality of holes. In this case, since edge parts of the optical sheet other than the edge part on the one long side are not supported, wrinkling or deflection does not occur in the optical sheet when thermally expanded.
However, in the structure in which the optical sheet is hooked by the positioning pins to be held, the optical sheet may move in a direction perpendicular to a surface thereof, and fluctuation occurs. In a situation in which strong vibrations are applied during a vibration test, transportation, or the like, peripheral edges of the optical sheet are rubbed by the fluctuation thereof to cause sheet damage. If there is sheet damage in the optical sheet, problems such as luminance unevenness, or a decrease in luminance may occur in the display apparatus.
A configuration is disclosed in which a backlight box for housing a light source has an inclination at a height of peripheral walls thereof, and peripheral edge parts of the optical sheet are held by end faces of the peripheral walls.
In particular, the disclosed backlight box is formed in a rectangular box shape with one surface open, and the height of a peripheral wall corresponding to one long side of a bottom of the box among four peripheral walls is higher than that of the peripheral wall corresponding to the other long side of the bottom of the box. In addition, peripheral walls corresponding to both of the short sides of the bottom of the box are configured so as to be lowered toward the other long side from the one long side, and peripheral end faces thereof are inclined with respect to the bottom at a prescribed angle. A diffusion plate is fixed to the peripheral end face, and hooking parts of the optical sheet are provided on the peripheral end face of the other long side.